A day after Italy’s constitutional court partially struck down a law that gave him blanket immunity from prosecution, the announcement adds a further headache for the premier, who is battling to shore up his struggling government and already faces fraud and corruption charges.

The magistrates are examining whether Berlusconi intervened improperly with police to secure the release of 17-year-old Karima El Mahroug, who uses the stage name “Ruby”, after she was held over theft allegations.

The investigation also covers allegations of underaged prostitution. The age of consent is 14 in Italy but exploiting or favouring prostitution of minors aged under 18 is a crime.
Prosecutors said in a statement they were investigating alleged crimes committed between February and May 2010, when the girl was 17 years old, and that they had issued summons to Berlusconi and his lawyers.

The prime minister’s lawyer Niccolo Ghedini issued a statement dismissing the investigation as “absurd and groundless” and said the allegations had already been denied by witnesses and those directly involved.

The case of “Ruby” caused an international media storm last year and instantly made the expression “bunga bunga”—a term used by the young woman to describe sex parties—part of the Italian vocabulary.

She told newspapers she was paid €7,000 after she attended a party at Berlusconi’s residence near Milan but she denied having sex with him.

Berlusconi, who has weathered a series of sex scandals involving escorts and young women since returning to power in 2008, has acknowledged knowing Ruby and making a phone call to police on her behalf.

But he says he was merely offering normal assistance to a person in need. He has denied using any improper influence or pressuring officers to let her go.  Berlusconi was placed under investigation last month but the probe was only made public on Friday.
The 74 year-old premier’s mounting legal woes have prompted speculation that his government, which just survived a no-confidence motion in parliament last month, may be close to collapse, bringing early elections to Italy. On Friday, Berlusconi told a TV news programme that the constitutional court ruling would not affect his government and he dismissed speculation that it would make early elections more likely.

“Yesterday’s decision by the constitutional court has absolutely no influence; the government will continue to go forward because the last thing Italy needs is early elections,” he told Canale 5 television.

A source with knowledge of the investigation said police were searching the office of a regional official close to Berlusconi who went to pick up the girl at the police station when she was released.

A news director at Berlusconi’s Mediaset broadcaster and a TV impresario are also under investigation in the case.